VCR - Is it possible to disable HiFi to Mono (Linear) switch for dropouts?

[useraxe]

Hello. I was wondering, has somebody ever managed to disable the switching of audio sources for a vhs tape whenever there's dropouts?
I've learnt to restore the HiFi track even with high amounts of noise and crackling, but something that bothers me is the audio switching to linear, which loses some quality and creates a blank in the audio on my main VCR. And for my other VCR, it switches too quickly giving a crackly sound.

Although I do wonder, does the switching happen because there is no HiFi information on that part, so there would only just be hissing?

[davexnet]

Have you tried adjusting the tracking to see if you can "dial in" the hifi audio
a little better?

[useraxe]

Same thing happens. I think it might be the same thing as video dropouts.

[davexnet]

Is the tape damaged? Drops out at the same place each time?
I don't know if what you have in mind is possible, might be vcr specific,
perhaps you should post the model info.
Have you tried cleaning the heads on the drum and giving the tape path
a clean?
Also the lower edge of the tape contains the control track.
Try cleaning the stationary head near the pinch roller, lower edge

[The_Doman]

Set it to MONO/Linear only?
Some VCR's let you set it to mixed HIFi/linear mode, but that will probably give more undesirable results.

The obvious thing to try is another VCR if you have that available.
Different brands/types VCR's can handle a problematic HiFi audio different/better/worse.
I have some tapes without any visible tracking problems where the HiFi audio plays terrible on my S-VHS JVC's but give no problem on other HiFi VCR's

[johnmeyer]

I had a VCR that made HiFi audio crackle. I was able to play the tapes just fine on another VCR. So the first thing I'd suggest is to try the tape on another VCR, if you have access to one.

If I were in your position and had to occasionally use the audio from the linear track, my approach would be to capture the tape twice, once with HiFi, and once with the linear track. I'd then put the video in my NLE with the two audio tracks below. I use Vegas, and I have a script that lets me duck between two audio tracks with a single push of a button, so I'd use that to switch between the HiFi and linear track. I'd set the duck to about 1-3 seconds in order to make the transition between the two tracks less jarring.

[useraxe]

Is the tape damaged? Drops out at the same place each time?
I don't know if what you have in mind is possible, might be vcr specific,
perhaps you should post the model info.
Have you tried cleaning the heads on the drum and giving the tape path
a clean?
Also the lower edge of the tape contains the control track.
Try cleaning the stationary head near the pinch roller, lower edge

The dropouts happen at the same place.
And it is Panasonic Nv-Hs950. Do you know if it's a stupid idea to solder wires to the HiFi audio pack board? I had an idea to do that, though at at first trying it on a vcr I don't care about. (I don't know if it's even possible yet, just had an idea after reading the service manual a bit.)

Set it to MONO/Linear only?
Some VCR's let you set it to mixed HIFi/linear mode, but that will probably give more undesirable results.

The obvious thing to try is another VCR if you have that available.
Different brands/types VCR's can handle a problematic HiFi audio different/better/worse.
I have some tapes without any visible tracking problems where the HiFi audio plays terrible on my S-VHS JVC's but give no problem on other HiFi VCR's

I do have another vcr that has the linear mode switch and I use that audio to fill in the HiFi dropouts, but the thing is I hoped there would be a way to do the same with the HiFi audio, disabling the mono one.

I had a VCR that made HiFi audio crackle. I was able to play the tapes just fine on another VCR. So the first thing I'd suggest is to try the tape on another VCR, if you have access to one.

If I were in your position and had to occasionally use the audio from the linear track, my approach would be to capture the tape twice, once with HiFi, and once with the linear track. I'd then put the video in my NLE with the two audio tracks below. I use Vegas, and I have a script that lets me duck between two audio tracks with a single push of a button, so I'd use that to switch between the HiFi and linear track. I'd set the duck to about 1-3 seconds in order to make the transition between the two tracks less jarring.

Currently the VCR I have is very good at dealing with low quality tapes, better than previous ones even after roller adjustments.

[timtape]

I'm an audio guy. I suspect you are right that disabling the crossfade/mute function will basically reveal the hiss in those signal dropout moments, just as with an FM radio receiver with no auto muting. I've not studied typical circuitry in HiFi playback but suspect it monitors the RF signal and mutes the audio output wherever the RF drops to a predefined level. We can see the designer's intention to maintain audio continuity via the crossfade to the linear track.

Much of the problem in the sample audio track below (starts 0:33 and sporadically though the track) is that the average level of the linear track inserted in the dropout sections is too low. Just matching the HiFi/linear levels upstream of the switching point would be an improvement, closer to what was intended by the designers of the crossfade circuit. Sometimes we have to make adjustments.

But that raises the general issue of making the best of the linear track playback even just for those short sections where it is inserted. Perhaps the most common reason for less than optimal playback of the linear track is the same as with compact audio cassettes: an azimuth error. But almost nobody seems to bother doing anything about fixing the error when it's present. The best most seem to do is to play the tape on various decks and use the deck which happens to give the clearest audio on the linear track, which is a pretty primitive method.

Some of us adjust P guides when it's needed for best picture but adjusting that one azimuth screw on the A/C head by 1/4 of a turn seems to some I've discussed this with, almost like permanently damaging the VCR. In the audio world, adjusting the playback head azimuth screw is much more common and accepted as part of the job, but with consumer video like VHS and Beta, not so much...
A broader issue can be the practice of recommending capture VCR makes and models solely on their picture resolving ability with audio performance not even rating a mention. But I digress...

Hope this helps.


https://youtu.be/-oOzdIr8fv8?si=LdzJVWrrNQ9JMC6Q

[useraxe]

I'm an audio guy. I suspect you are right that disabling the crossfade/mute function will basically reveal the hiss in those signal dropout moments, just as with an FM radio receiver with no auto muting. I've not studied typical circuitry in HiFi playback but suspect it monitors the RF signal and mutes the audio output wherever the RF drops to a predefined level. We can see the designer's intention to maintain audio continuity via the crossfade to the linear track.

Much of the problem in the sample audio track below (starts 0:33 and sporadically though the track) is that the average level of the linear track inserted in the dropout sections is too low. Just matching the HiFi/linear levels upstream of the switching point would be an improvement, closer to what was intended by the designers of the crossfade circuit. Sometimes we have to make adjustments.

But that raises the general issue of making the best of the linear track playback even just for those short sections where it is inserted. Perhaps the most common reason for less than optimal playback of the linear track is the same as with compact audio cassettes: an azimuth error. But almost nobody seems to bother doing anything about fixing the error when it's present. The best most seem to do is to play the tape on various decks and use the deck which happens to give the clearest audio on the linear track, which is a pretty primitive method.

Some of us adjust P guides when it's needed for best picture but adjusting that one azimuth screw on the A/C head by 1/4 of a turn seems to some I've discussed this with, almost like permanently damaging the VCR. In the audio world, adjusting the playback head azimuth screw is much more common and accepted as part of the job, but with consumer video like VHS and Beta, not so much...
A broader issue can be the practice of recommending capture VCR makes and models solely on their picture resolving ability with audio performance not even rating a mention. But I digress...

Hope this helps.


https://youtu.be/-oOzdIr8fv8?si=LdzJVWrrNQ9JMC6Q

Thank you for the tip, but I've already adjusted the linear head azimuth to sound good (loud, sharpest) on majority of tapes. And adjusting it on every tape is out of the question, as my main vcr doesn't have a way of switching to linear manually, only to mix it with hifi.

But the bigger problem is when the switching does happen, it insterts a blank for ~117ms, which can remove a sentence of people speaking. On my older Panasonic, the switching is instant like in the sample you provided, but when there's lots of dropouts, the sound makes lots of crackling from the fast switching, which isn't pleasant to listen to even after restoring filters.

[timtape]

OK. What filters are you using to deal with the noises?

[timtape]

Ideally both audio streams would be captured , the HiFi with no defaulting to linear, and the linear, each on separate digital tracks. Otherwise we're left, as you say, with the deck making the decisions as to which of either track is captured at any given moment.

As an example, typically HiFi tracks in better VHS decks allowed manual adjustment of recording levels to tape. This was a good feature but left open the risk of an unskilled operator setting too high or low a record level, and the resultant noise or distortion. In playback a VCR may play such a distorted HiFi section of tape without defaulting to the less distorted linear. Hence having the complete linear track, and digitised in the same pass as the picture and HiFi track, is a quicker process and offers more audio editing choices in post.

[useraxe]

Acon digital declick. Good at default settings, and sometimes adding m/s mode helps with preserving "phantom center channel" in the center.

And yeah, sad there isn't a way of ripping all 3 channels.

[timtape]

Yes I've found a good Declick tool very useful tool for HiFi clicks although obviously it can only do so much. Glad you found it.

Capturing all 3 tracks (or 4 with linear stereo) is quite possible with some electronic mods to a VCR, tapping into the signals upstream of the switching point, possibly adding some impedance buffering/ level matching, and out to some RCA sockets. I would do it if a particular project came up to make it worth doing.

I have an old Panny AG 7350 which has separate outputs for HiFi stereo and linear stereo but I think the HiFi outputs still default to linear with dropouts. I must check it again.